Childhood abuse is an important public health problem; however, little is known about the effects of abuse on the brain and neurobiological development. This article reviews the behavioral and biological consequences of childhood abuse and places them in a developmental context. Animal studies show that both positive and negative events early in life can influence neurobiological development in unique ways. Early stressors such as maternal separation result in lasting effects on stress-responsive neurobiological systems, including the hypothalamic-pituitary-adrenal (HPA) axis and noradrenergic systems. These studies also implicate a brain area involved in learning and memory, the hippocampus. in the long-term consequences of early stress. Clinical studies of patients with a history of abuse also implicate dysfunction in the HPA axis and the noradrenergic and hippocampal systems; however, there are multiple questions related to chronicity of stress, developmental epoch at the time of the stressor, presence of stress-related psychiatric disorders including posttraumatic stress disorder and depression. and psychological factors mediating the response to trauma that need to be addressed in this field of research. Understanding the effects of abuse on the development of the brain and neurobiology will nevertheless have important treatment and policy implications.